我想出了如何从Kotlin的片段中正确地做到这一点，以捕获图像并处理返回的位图。在其他情况下也是一样的。

首先，您必须注册片段以侦听活动结果。这必须在初始化片段之前完成，这意味着创建一个成员变量，而不是在onCreate函数中初始化。

class DummyFragment : Fragment() {

  //registering fragment for camera listener
  private val takePhoto = registerForActivityResult(
    ActivityResultContracts.StartActivityForResult()
  ) {
    if (it.resultCode == Activity.RESULT_OK) {
      val imageBitmap = it.data?.extras?.get("data") as Bitmap
      // do your thing with the obtained bitmap
    }
  }

  override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
  }

}

然后，像你通常做的那样调用摄像机意图。并使用上面创建的变量来启动意图。

override fun onCreate(savedInstanceState: Bundle?) {
  super.onCreate(savedInstanceState)
  someRandomButton.setOnClickListener {
    val takePictureIntent = Intent(MediaStore.ACTION_IMAGE_CAPTURE)
    takePhoto.launch(takePictureIntent)
  }
}

startActivityForResult和onActivityResult在android 10 API 30中已弃用，现在我们有了一种新的方法来使用registerForActivityResult来获得结果

resultContract =
    registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
        if (result.resultCode == Activity.RESULT_OK) {
            // There are no request codes
            val country = result.data?.getParcelableExtra<Country>("Country")
            showLiveDemoDialogue(country)
        }
    }

并启动活动

val intent = Intent(this, CountriesListActivity::class.java)
        resultContract.launch(intent)

但你应该在呼叫发射前注册然后发射到你想去的任何地方。 否则，您将得到这个异常

attempting to register while current state is RESUMED. LifecycleOwners must call register before they are STARTED.

我的目标是用最少的代码更改重用startActivityForResult方法的当前实现。为此，我使用onActivityResultFromLauncher方法创建了一个包装器类和接口。

interface ActivityResultLauncherWrapper {

    fun launchIntentForResult(activity: FragmentActivity, intent: Intent, requestCode: Int, callBack: OnActivityResultListener)

    fun unregister()

    interface OnActivityResultListener {
        fun onActivityResultFromLauncher(requestCode: Int, resultCode: Int, data: Intent?)
    }
}

class ActivityResultLauncherWrapperImpl : ActivityResultLauncherWrapper {
    private var weakLauncher: WeakReference<ActivityResultLauncher<Intent>>? = null

    override fun launchIntentForResult(
            activity: FragmentActivity,
            intent: Intent,
            requestCode: Int,
            callBack: ActivityResultLauncherWrapper.OnActivityResultListener
    ) {

        weakLauncher = WeakReference(
                activity.registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
                    callBack.onActivityResultFromLauncher(requestCode, result.resultCode, result.data)
                }
        )

        weakLauncher?.get()?.launch(intent)
    }

    override fun unregister() {
        weakLauncher?.get()?.unregister()
    }
}

我在我的项目中使用匕首，我在需要的地方注入了包装器

@Inject
lateinit var activityResultLauncher: ActivityResultLauncherWrapper

但是包装器也可以直接实例化:

val activityResultLauncher = ActivityResultLauncherWrapper()

然后你必须用launchIntentForResult改变startActivityForResult方法。下面是一个从片段中调用它的例子:

activityResultLauncher.launchIntentForResult(
        requireActivity(),
        intent,
        REQUEST_CODE_CONSTANT,
        object: ActivityResultLauncherWrapper.OnActivityResultListener {
            override fun onActivityResultFromLauncher(requestCode: Int, resultCode: Int, data: Intent?) {
                /*do something*/
            }
        }
)

您将在匿名对象中收到结果。 你可以在Fragment或FragmentActivity中使用OnActivityResultListener，如果你实现了接口，并像这样重构当前的实现:

class MyFragment : Fragment(), OnActivityResultListener {
   
 ...
    
override fun onActivityResultFromLauncher(requestCode: Int, resultCode: Int, data: Intent?) {/*do somthing*/}

 ...

}

正如我们所知，Kotlin类ActivityResultLauncherWrapper也可以在java代码中使用。在我的项目中也有java类。这里有一个在Fragment中实现回调接口的例子:

public class MyFragment extends Fragment implements OnActivityResultListener {
    
...

    @Inject
    ActivityResultLauncherWrapper activityResultLauncher;
//ActivityResultLauncherWrapper activityResultLauncher = new ActivityResultLauncherWrapper()

...

public void launnchActivity(@NotNull Intent intent) {
        activityResultLauncher.launchIntentForResult(requireActivity(), intent, REQUEST_CODE_CONSTANT, this);
    }

...

 @Override
    public void onActivityResultFromLauncher(int requestCode, int resultCode, Intent data) {/*do somthing*/}
...
}

我希望这有助于为您的案例构建解决方案。

您可以为Koltin使用扩展函数。例如:

//random utils file
fun Fragment.buildGetContentRequest(function: (Uri) -> Unit): ActivityResultLauncher<String> {
    return this.registerForActivityResult(ActivityResultContracts.GetContent()) {
        function(it)
    }
}

fun Fragment.buildTakePhotoRequest(function: (Boolean) -> Unit): ActivityResultLauncher<Uri> {
    return this.registerForActivityResult(ActivityResultContracts.TakePicture()) {
        function(it)
    }
}

fun Fragment.buildSelectMultipleContentRequest(function: (MutableList<Uri>?) -> Unit): ActivityResultLauncher<String> {
    return this.registerForActivityResult(ActivityResultContracts.GetMultipleContents()) {
        function(it)
    }
}

然后在你的片段中像这样

//your actual fragment logic
class YourFragment : Fragment() {
    //we can assign our request in init process
    private val mRequestSelectFiles = buildSelectMultipleContentRequest { 
        onFilesSelected(it) 
    }


    fun onSelectFiles() {
        val mime = "*/*"
        mRequestSelectFiles.launch(mime)
    }

    fun onFilesSelected(list: MutableList<Uri>?) {
        //your logic
    }
}

结合上面的答案，我有一个与旧方法兼容的方法startActivityForResult()保持使用requestCode而不改变旧的代码结构:

ActivityLauncher.class

public class ActivityLauncher {

private final ActivityResultLauncher<Intent> launcher;
private ActivityResultCallback<ActivityResult> activityResultCallback;

private ActivityLauncher(@NonNull ActivityResultCaller caller,
                         @NonNull ActivityResultContract<Intent, ActivityResult> contract,
                         @Nullable ActivityResultCallback<ActivityResult> activityResultCallback) {
    this.activityResultCallback = activityResultCallback;
    this.launcher = caller.registerForActivityResult(contract, this::onActivityResult);
}

public static ActivityLauncher registerActivityForResult(
        @NonNull ActivityResultCaller caller) {
    return new ActivityLauncher(caller, new ActivityResultContracts.StartActivityForResult(), null);
}

public void launch(Intent intent, @Nullable ActivityResultCallback<ActivityResult> activityResultCallback) {
    if (activityResultCallback != null) {
        this.activityResultCallback = activityResultCallback;
    }
    launcher.launch(intent);
}

private void onActivityResult(ActivityResult result) {
    if (activityResultCallback != null) activityResultCallback.onActivityResult(result);
}

public interface OnActivityResult {
    void onActivityResultCallback(int requestCode, int resultCode, Intent data);
}

}

在BaseActivity.java中代码

private final ActivityLauncher activityLauncher = ActivityLauncher.registerActivityForResult(this);

public void startActivityForResult(Intent intent, int requestCode, ActivityLauncher.OnActivityResult onActivityResult) {
    activityLauncher.launch(intent, result -> onActivityResult.onActivityResultCallback(requestCode, result.getResultCode(), result.getData()));
}

最后在每个扩展BaseActivity的Activity中，实现ActivityLauncher。将覆盖函数“OnActivityResult”的名称改为“onActivityResultCallback”。还记得删除super.onActivityResult()

如何使用:startActivityForResult(intent, requestCode, this)

在芬兰湾的科特林 我改变了我的代码

startActivityForResult(intent, Constants.MY_CODE_REQUEST)

and

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent) {
    super.onActivityResult(requestCode, resultCode, data)
    if (resultCode == Activity.RESULT_OK) {
        when (requestCode) {
            Constants.MY_CODE_REQUEST -> {
            ...
}

to

registerForActivityResult(StartActivityForResult()) { result ->
    onActivityResult(Constants.MY_CODE_REQUEST, result)
}.launch(intent)

and

private fun onActivityResult(requestCode: Int, result: ActivityResult) {
    if(result.resultCode == Activity.RESULT_OK) {
        val intent = result.data
        when (requestCode) {
            Constants.MY_CODE_REQUEST -> {
            ...

我希望这对你有用。: D